<?php
/**
 * Slipstream :: Highly adaptive dependency injection framework
 * Copyright 2010-2011 Ian Unruh (Xerof3ar)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace Slipstream\Infrastructure\Context\Type;

use ArrayObject;
use Slipstream\Configuration\ContextInterface;

/**
 * Identifier resolver that caches resolved identifiers in memory
 *
 * Benchmarks show the cached resolver service performs up to 20x
 * faster than the uncached resolver service.
 *
 * @author Ian Unruh (Xerof3ar) <ianunruh@gmail.com>
 * @since Class avaliable since release 1.0
 */
class CachedResolverService extends ResolverService
{
	/**
	 * @var ArrayObject<string:string>
	 */
	protected $cachedTypes;
	
	/**
	 * Class constructor
	 * @return void
	 */
	public function __construct()
	{
		parent::__construct();
		$this->cachedTypes = new ArrayObject();
	}
	
	/**
	 * Attempts to resolve a context to a class or interface type
	 *
	 * @param ContextInterface $context
	 * @return string|false Returns false if identifier could not be resolved
	 */
	public function resolveType(ContextInterface $context)
	{
		$contextPath = $context->getPath();
		if(!$this->cachedTypes->offsetExists($contextPath)) {
			$identifier = parent::resolveType($context);
			$this->cachedTypes->offsetSet($contextPath, $identifier);
		}
		return $this->cachedTypes->offsetGet($contextPath);
	}
	
	/**
	 * Clears resolved identifiers from the cache
	 * @return void
	 */
	public function clearCache()
	{
		$this->cachedTypes = new ArrayObject();
	}
}